Liver Function Tests

Question 1

AST and ALT are enzymes which exist in the liver. What is their significance in liver function tests?

Answer 1

These are liver enzymes and so their levels are elevated when there is any sort of hepatocyte damage

Question 2

What is the significance of gamma glutamyl transpeptidase in a liver function test?

Answer 2

This allows you to see whether an elevation in alkaline phosphatase levels is to do with the liver or any tissue - if it is related to liver pathology then GGT will also be elevated, if not it is not likely to be due to liver pathology.

Question 3

What liver conditions can markedly elevated alkaline phosphatase levels indicate?

Answer 3

Ductal obstruction
Cholestasis
Infiltration of liver by a tumour

Question 4

Why is it useful to look at prothrombin time as part of a liver function test?

Answer 4

All clotting factors are produced in the liver and so am increase in prothrombin time could indicate liver pathology if the liver has been unable to synthesise the clotting factors

Question 5

What are liver function tests used for?

Answer 5

Well person screening
Investigation of unexplained symptoms
Investigation of symptoms suggestive of liver disease
Preoperative baseline assessment
Monitoring of established liver disease
Monitoring of response to treatment

Question 6

What is the cut-off level at which a person would be considered to have unconjugated hyperbilirubinaemia?

Answer 6

Greater than 85% of total bilirubin is unconjugated

Question 7

What is the cut-off level at which a person would be considered to have conjugated hyperbilirubinaemia?

Answer 7

Greater than 50% of total bilirubin is conjugated

Question 8

Is AST or ALT more liver specific?

Answer 8

ALT

Question 9

In what tissues are AST and ALT present in?

Answer 9

Cardiac and skeletal muscle
Kidneys
Brain
Pancreas
Lungs
Leukocytes
RBCs
Liver

Question 10

AST is present in both cystolic and mitochondrial isoenzymes. T/F?

Answer 10

True

Question 11

What factors are part of a conventional LFT profile?

Answer 11

Bilirubin
Albumin
ALT
AST
ALK
GGT
Total protein

Question 12

GGT can be used to see if alcoholics are refraining from alcohol use. How is this possible?

Answer 12

The consumption of alcohol will induce increased production of GGT

Question 13

On which chromosome are the genes for bone ALK and liver ALK?

Answer 13

Chromosome one

Question 14

What is the half life of albumin?

Answer 14

17-20 days

Question 15

LFTs are indicative of the severity of underlying disease. T/F?

Answer 15

False

Question 16

When presented with a patient with possible liver disease what symptoms are important to ask about in the systemic enquiry?

Answer 16

Weight loss
Anorexia
Vomiting
Pain
Myalgia
Jaundice
Pruritus
Change of colour of urine and stool

Question 17

When presented with a patient with possible liver disease it is important to ask about potential exposure to hepatotoxins such as…?

Answer 17

Alcohol
Medications
Other chemicals

Question 18

When presented with a patient with possible liver disease it is important to ask about family history of which diseases?

Answer 18

Viral hepatitis

Heritable liver disease

Question 19

When presented with a patient with possible liver disease it is important to ask about potential exposure to viruses. How might a person have been exposed to such viruses?

Answer 19

Sexual transmission
Travel
Transfusion
IV drug use

Question 20

If a person has a decreased ALK then this may indicate hepatocellular disease. How might a result of normal or decreased albumin influence diagnosis?

Answer 20

Normal - acute hepatitis

Decreased - chronic hepatitis

Question 21

If serum ALK is increased but serum GGT is normal on an LFT what might this indicate?

Answer 21

Possible bone disease